Wheel wear sensing device and compensator



May 8, 1962 G. E. wEsPl WHEEL WEAR SENSING DEVICE AND COMPENSATOR FiledMrch 13, 1961 2 Sheets-Sheet 1 May 8, 1962 G. E. wEsPl 3,033,187

WHEEL WEAR SENSING DEVICE AND COMPENSATOR Filed March 13, 1961 2Sheets-Sheet 2 AMPL/F/E CRYSTAL 'FICK P I VENTOR .GEUHGE E. WEE/Ill ATTOENEY 3,933,187 WHEEL WEAR SENSNG DEVICE AND CMPENSATOR George E. Wespi,Lyons, lli., assigner to Norton Company, Worcester', Mass., acurporation of Massachusetts Filed Mar. 13, 196i, Ser. No. 95,399 l2Claims. (Cl. iid-11) rThis invention relates to grinding apparatus ofthe kind in which a grinding wheel is arranged to be moved toward a worksupport a predetermined amount to grind a work piece mounted on the worksupport to size, and, in particular, to machines of the kind shown inPatent No. 2,894,360 issued to Charles C. Alvord on July l4, 1959, inwhich reference may be had to details disclosed therein.

IIn machines of the foregoing kind, it is customary to dress the face ofthe grinding wheel periodically, either manually or automatically, bypredetermined amounts to maintain the wheel true, and hence to insureaccuracy in the grinding operation. However, dressing the wheel reducesits radius so that the finished Work will be oversize by the amountremoved from the radius of the wheel, if the Wheel is advanced towardthe Work by the wheel feed mechanism from the same starting point andthrough the same distance that the wheel was advanced by the wheel feedmechanism prior to the dressing operation. For this reason, it has beencustomary to provide a compensating mechanism responsive to theoperation of means for dressing the wheel and effective to adjust thewheel feed mechanism by a predetermined fixed amount calculated tooffset the reduction in the wheel radius resulting from the dressingoperation.

Under favorable circumstances when such a compensating mechanism isproperly adjusted such an arrangement tends to minimize deviations inthe finished size of successive work pieces from the finished sizeprescribed for such work pieces. However, since successive reductions inthe radius of the grinding wheel may not in fact be uniform over anextended period due to the intervention of other modifying factors,there is no positive assurance that such compensation will remaineffective over extended periods without occasional supplemental manualadjustment of the Wheel feed mechanism.

The ultimate requirement for grinding successive work pieces to auniform prescribed size is simply that the periphery of the grindingwheel come to rest at the end of each feeding cycle at the samepredetermined distance from the axis upon which the successive workpieces are supported for the grinding operation, notwithstanding theintervention of wheel size modifying factors such as wheel wear,dressing operations, and dressing tool wear.

Accordingly, the present invention contemplates an arrangement forprecise direct measurement of the radius of the grinding wheel operableto adjust the wheel feeding mechanism so that the ultimate position ofthe surface of the grinding wheel during a grinding operation coincideswith the predetermined precise location in which the grinding wheel willproduce uniformly sized successive work pieces to the desired finisheddimension. The device comprising the instant invention is furthercharacterized by the fact that it automatically compensates for the neteffect of the various different factors tending to adversely effect thefinal sizing of a succession of work pieces finished on a given grindingmachine.

An object of this invention is the provision of automatic compensatingmeans for the wheel feeding mechanism of a grinding machine controlledby a sensing element arranged for displacement into direct engagementwith the surface of a grinding wheel after a truing operation thereon,and actuating means therefor coupled with the truing apparatus forcoordinated operation therewith.

Another object of this invention is to provide a means CAD Patented May8, 1962 for periodically adjusting the Wheel feeding mechanism of agrinding machine to compensate for the net change in the size of thegrinding wheel since the preceding compensation of the wheel feedingmechanism.

Still another object is the provision of automatic compensating meansfor the Wheel feeding mechanism of a grinding machine including meansfor advancing a sensing element toward the surface of the grinding wheeland means for advancing the grinding wheel toward a Work piececoncurrently through the same distance until these means are inactivatedsimultaneously by engagement of the sensing element with the surface ofthe grinding wheel. v

A further object of this invention is the provision of an automaticcompensating means for the wheel feeding mechanism of a grinding machineoperable periodically to adjust the setting of the wheel feedingmechanism to compensate for the net change in wheel size including adirect sensing element normally disposed a predetermined short distancefrom the surface of the grinding wheel,

initially advanced toward the surface of the grindingY wheel saidpredetermined distance prior to a compensating operation, and retractedfrom the surface of the grinding wheel said predetermined distance uponcompletion of a compensating operation.

As herein illustrated, there is a relatively fixed work support, agrinding wheel, and a grinding wheel slide supporting the grinding wheelrotatably thereon for movement therewith toward the work support to feedthe wheel toward the work. In accordance with the invention, there is awheel dressing tool mounted for movement transversely of the face of thegrinding wheel and back through a cycle for dressing the face of thewheel, a stylus adjacent the face of the wheel, means for initiallypositioning F the stylus and grinding wheel slide predeterminedcoordinated distances from the face of the wheel and the work supportrespectively, means operable at the end of each cycle of operation ofthe dressing tool to advance the stylus a predetermined amount and thento effect concurrent movement of the stylus and the wheel slide equaldistances toward the wheel and Work support respectively, and meansoperable when the stylus touches the wheel to render the last-namedmeans inoperable and then to retract the stylus the same predeterminedamount. A crossslide supports the dressing tool for reciprocablemovement relative to the face of the wheel and there is means on thecross-slide operable, as the slide nears the end of a cycle ofoperation, to initiate operation of the means for advancing the stylusand wheel slide toward the wheelk and work support respectively. Themeans for advancing the stylus and wheel slide includes fiuid operatedmotors, one of which is actuated to advance the stylus toward the wheelby the amount of the previous retraction and the others of which areoperable to advance the stylus and the slide simultaneously equalamounts.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

FIG. l is a fragmentary side elevation partly in section of a grindingapparatus showing a work support, a grinding wheel, a screw foradvancing the wheel toward the work support, a dressing tool, andcompensator mechanism including a sensing device;

FIG. 2 is a section on a larger scale taken on the line 2 2 of FIG. l;

FIG. 3 is a section taken on the line 3 3 of FIG. 1;'

Referring to the drawings, the machine has a rigid base on which thereare spaced parallel, horizontally disposed ways 12, which support agrinding wheel 14 and wheel slide 16 for movement toward and away from awork supporting table 1S, the latter being mounted for movementtransversely of the face of the grinding wheel on V-shaped and flat Ways20 and 22 on the base 10. The wheel slide 16 has a half nut 26 securedto its underside and threadably engaged with a feed screw 24 journaledin the base for axial and rotational movement to advance the slide 16toward the work support. For rapid feed the rear end of 4the feed screw24 is journaled in a bearing slide 11 which is operably connected to afluid motor 13, whereby the feed screw may be advanced bodily axiallythereof without rotation to move the wheel slide 16 up to the worksupport. For slow feed the forward end of the feed screw 24 has anUnthreaded portion which is slidably keyed in the rear end of a sleeve15, the latter being rotatably supported on the base 16. A spindle 17 isslidably keyed at its rear end in the forward end of the sleeve 15 andextends forwardly therefrom beneath the work support into a gear housing19. A drive gear 21 is keyed to the forward end of the spindle andaffords means by which the feed screw 24- may be automatically ormanually rotated. Automatic rotation of the feed screw is effectedthrough a pair of gears 23 and 25, one of which meshes with the drivegear 21, and the other of which meshes with a rack 27. The rack 27 isformed on one side of a piston 29 situated in a cylinder 31. Bysupplying pressure fluid to one end of the cylinder 31 the rack may bemoved in a direction to advance the wheel slide. For manual feed thegear 23 is disengaged from the drive gear 21 and rotation is imparted tothe latter by a gear 33 which meshes therewith. The gear 33 is keyed toa shaft 3S journaled in the gear housing 19 and the shaft 35 has fixedto it an index gear 39 that meshes with a pinion of a well knownmicrometer adjusting means supported on a hand wheel 37 rotatable on theend of the shaft 35. This micrometer adjusting means arranged tocooperate with an adjustable stop for controlling the work size mayconveniently correspond to the micrometer adjusting device described andillustrated in Patent No. 2,572,529 issued to H. A. Silven on October23, 1951. In this Silven patent, particular reference may be had to thedescription beginning in column 19 and to the showing in FIGS. 9 and l0.

A motor M is mounted on the wheel slide and belts 32 entrained aboutpulleys 28 and 30 on the motor shaft and wheel shaft respectively,provide for driving the grinding wheel.

At the top of the Wheel guard 34 there is a horizontal opening 36 aroundwhich is formed a support 38 for a dressing tool 46 which projectsdownwardly through the opening, as shown in FIG. 6, close to the surfaceof the grinding wheel 14. The dressing tool 4S is xed to the lower endof a spindle 42 which is vertically adjustable in a sleeve 44 mountedbetween pairs of guides 45 on a slide 46. The slide 46 has a dove-tailrecess engaged with a dove-tailed projection from a rail 48 supported bya bracket 50 in a horizontal position crosswise of the grinding wheel,that is, parallel to its axis of rotation. A hand wheel 54 and gearingS6 provide means for adjusting the tool 4t, heightwise and a pin 53,engageable with one of the gears 56, provides means for fixing the tool4t) at a predetermined heightwise position. A knife edge follower 47,also fixed to the sleeve 64, and bearing on a form bar 49, guides thetool 4t? as it moves transversely of the face of the grinding wheel.

With the dressing tool adjusted before each cycle to the desiredposition either automatically or manually for removing a predeterminedamount from the face of the wheel, movement back. and forth across theface of the wheel is effected by reciprocation of the slide 46 and tothis end the latter is connected by a rod 62 to a piston 64, situated ina uid motor` cylinder 66. The cylinder 66 is mounted on or formedintegrally with the rail 48. Pressure fluid is supplied to the oppositeends of the fluid motor cylinder 66 and vented therefrom by way of avalve V1 to which uid is supplied from a reservoir 68, through a conduitC1, and exhaust fluid is returned to the reservoir from valve V1 by wayof a conduit C2. When the valve V1 is shifted to the left, fluid issupplied to the left end of the fluid motor cylinder 66 and, when it isshifted to the right, fluid is supplied to the right end of the fluidmotor cylinder 66. The slide 46 is reciprocated from left to right andback during one cycle of operation, to dress the face of the wheel and,as will appear hereinafter, this reciprocation may be effectedautomatically or manually.

Each time the face of the grinding Wheel is dressed its diameter is madesmaller hence it is evident that if the machine has been set to feed theslide forwardly a predetermined amount to grind the work to a specifieddimension, unless provision is made for compensating for the modifyingfactors tending to change diameter of the wheel, the dimensionultimately ground will not be the predetermined required size. Torectify this, a sensing device 70 (FIG. 1) is mounted adjacent thegrinding wheel for detecting directly the net change in wheel radius.This sensing device 70 is operable through control of a compensator 71to move the grinding wheel forwardly toward the work support by exactlythe same radial amount that is removed from the surface of the grindingwheel. The sensing device 70 is mounted on the wheel guard 34,rearwardly of the dressing tool, over a suitable opening formed in thewheel guard, and includes a stylus 72 (FIGS. 2 and ll), which is adaptedto be moved toward the surface of the grinding wheel 14, following eachdressing operation, by means which will be described hereinafter. Thecompensator device 71 incorporated in the lead screw slow feedingmechanism moves the wheel slide toward the work support including worktable 18 a corresponding amount by rotating the screw, independently ofthe automatic and manual means for feeding the wheel slide. When thestylus contacts the grinding wheel it actuates a circuit controllingmeans operable to terminate rotation of the lead screw and hence forwardmovement of the wheel slide, and also operable to retract the stylus bya predetermined amount so that it will not be damaged.

The stylus 72 is supported within a bushing 76 in turn yieldablysupported within the exposed end of sleeve 74 (FIG. 2) by a threadedcollar 73 screwed into the end of the sleeve 74. As illustrated in FIG.2, the bushing 76 is normally biased into fixed relation to the threadedcollar 78 by a combination of elements including a flange projectingfrom the bushing 76 and a biasing spring compressed between one face ofthe flange and one side Wall of a hollow annular retainer the other sidewall of which is disposed between and engaged by the other face of theflange on bushing 76 and the inner surface of the threaded collar 78.Thus, the stylus 72 is normally maintained by the biasing spring infixed axial relation to the sleeve 74, but it may be displaced tominimize damage to the stylus in the event the sleeve 74 is advanced toofar toward the surface of the grinding wheel.

The sleeve 74 is mounted on a lead screw 30, being supported near oneend by a ball bearing assembly 82, and at the other end by a threadednut 84 secured against rotation relative to sleeve 74 by the screw 85 sothat rotation of the screw effects movement of the sleeve axially of thescrew. The sleeve and screw are enclosed within a housing 86 having aange 88 at one end, by means of which it is bolted to the wheel guard34, and a flange at the other end to which is bolted a head casting 90containing a thrust bearing retainer 92 and ball bearing assemblies 94which support the lead screw 80 at that end of the housing. At the endof the housing adjoining the exposed end of sleeve 74 there is abellowstype diaphragm 96 extending between the lower extremity of thesleeve and the housing to exclude dust. The diaphragm 96 mayconveniently serve also as the means of preventing rotation of sleeve 74relative to housing 86 when lead screw 80 is rotated.

The actuating means for the sensing device 70 includes two coactingportions. The portion described first below s that which functions toadvance the stylus by a predetermined amount in preparation for agrinding Wheel size sensing operation and to retract the stylus from theface of a grinding wheel after such a sensing operation. The otherportion described thereafter is that which functions to advance thestylus further toward the wheel until it engages the surface of thewheel. A worm wheel 98 is fastened to the right end of the lead screw 80and this meshes with a worm 100 on a shaft 102 in the head casting 90.One end of the shaft 102 is journaled in a ball bearing assembly 104(FIG. 3) and the other end is rotatably supported in a sleeve bearing106, the latter constituting an end wall of a cylinder 108 within whichthere is situated a piston 110. The left-hand end of the shaft 102,beyond the bearing 106, has a collar 112 fixed thereto and between thiscollar and the left-hand side of the bearing 106 there is a coiledspring 114, the effect of which is to hold the shaft 102 and the piston110 engaged thereby displaced toward the left as viewed in FIG. 3, butwhich will permit the shaft to be moved axially toward the right. In theabsence of fluid pressure within the cylinder 108 at the left side ofthe piston 110, the spring 114 operates to retract the stylus from theface of the grinding wheel by a predetermined amount, for example, 0.01.

The shaft 102 has splined on it a clutch disc 116 (FIG. 6) on whichthere is mounted an externally toothed clutch ring 118, the lattermeshing with a rack 120 on one side of a piston 122 disposed in acylinder 124 which forms a part of the head casting 90. The clutch disc116 and ring 118 and the spring biased rollers therebetween constitute aone-way clutch. A spring 126 holds the piston at one end of thecylinder. However, by supplying oil to that end of the cylinder, thepiston may be moved toward the opposite end and, by such movement,rotate the ring 118 in a clockwise direction as seen in FIG. 6.Clockwise rotation of the ring 118 imparts a corresponding clockwiserotation to the disc 116 and hence to the worm 100 so as to turn theworm wheel 98 in the direction of the arrow shown in FIG. 6 and thus toadvance the sleeve 74 and hence the stylus 72 toward the wheel 14. Whenthe cylinder 124 is vented, the one-way clutch allows the spring 126 toreturn the piston 122 to its initial position without reversing rotationof the worm.

The compensator device 71 for advancing the grinding wheel at the end ofeach dressing operation to make up for the loss in radius of the wheelas illustrated and described herein is the same as the correspondingportion of Patent No. 2,894,360 referred to above, to which referencemay be had for further information regarding this device. As previouslymentioned, the compensator device 71 is controlled by the sensing stylus72 and consists of a hollow piston rod 132 (FIG. 6), the left end ofwhich is slidably disposed in an axial chamber 134 at the right end asseen in FIG. l of the spindle 17, the latter being supported at itsforward end by a pair of ball bearing assemblies 142 in the gear housing19 supported by the base 10.

The right-hand end of the hollow piston rod 132 has on its outer surfacea rack 148 which meshes with a gear 150 (FIGS. 1 and 6), so thatmovement of the piston rod 132 to the right effects counter-clockwiserotation of the gear 150. The gear 150 rotates a stub shaft 152 on whichthere is a gear 154 which meshes with a gear ring 156 (FIGS. 4 and 6),surrounding a disc 157 secured to a worm shaft 158. Spring biasedrollers 159 situated in notches between the disk and ring provide a oneway clutch for driving the Worm shaft 158 clockwise when the gear ring156 is driven in a clockwise direction, as shown in FIG. 5. A similarone way clutch is provided at the other end of the shaft 158 to preventreverse rotation of the worm 161 mounted on shaft 158 when the gear 156is freely rotated counter-clockwise by the movement of the piston 132 tothe left. The worm 161 fixedly secured to worm shaft 158 meshes with aworm wheel 160 keyed to the spindle 17 and so is operable to effectrotation of the spindle independently of the hydraulically actuated rack27 or the hand wheel 37 and, by such rotation, to affect movement of thewheel slide forwardly toward the work support.

The hollow piston rod 132 has in its open end a slidably disposed pin128, the inner end of which is engaged with a compression spring 135. Ascrew 130, threaded into the gear housing 19 in turn supported by thebase 10, engages the outer end of the pin 128 and thereby constrains pin128 against displacement to the right as seen in FIG. 6. Thus, pin 12Sin cooperation with spring 135 returns piston rod 132 to the left end ofthe cylinder when the pressure is vented from that end of the cylinder.

Referring to FIG. 6, for the operation of the machine, the oil for -thesystem is supplied thereto from the reservoir 68 by a motor driven pump162 of conventional design by way of the conductor C1 and is returnedthrough a conductor C2, there being a relief valve V adjacent thedischarge side of the pump for by-passing oil from the conductor C1directly to the conductor C2 so that the pressure within the system maybe maintained at the desired constant level. Energy is supplied to thepump motor through a switch SW4 when the main switch SW1, connecting theelectrical system to the power line L1 has been closed. A motor M drivesthe grinding wheel 14,

as previously indicated, and this motor is energized by closing a switchSW2.

Reciprocation of the dressing tool 40 is effected by supplying oil firstto one end and then the other of the cylinder 66. The slide 46 movesfrom left to right and back for each cycle of operation and normallyoccupies a position of rest at the left-hand side, as shown in FIG. 6.When the slide is in the left-hand position it contacts a springpressedplunger 164 which holds a normally open switch LS3 at that side closed.At the same time, a normally closed switch LS2 at the opposite side isheld closed by a spring-pressed plunger 166. When the slide is in thelefthand position, if the main switch SW1 is closed, continuousreciprocation of the dressing tool may be initiated by closing a switchSW3 which allows current to flow to relay CRL Energization of relay CR1operates to shift switch ICR to the left, thus energizing solenoid S1.Relay CRI is held energized through the normally closed switch L82.Solenoid S1 shifts a spool in the valve V1 to the left, thus permittingoil to ow through it to the left end of the cylinder 66 and at the sametime vents oil from the right end. Consequently, the piston 64 moves tothe right. When the slide 46 moves from left to right it first opensswitch LS3 by releasing the plunger 164, but relay CRI remains energizedby means of the holding circuit therefor through normally closed switchL52. As slide 46 approaches the right-hand end of its stroke, it `opensswitch L82 by engagement with the plunger 1.66, thereby deenergizingrelay CRI, opening switch 1CR and de-energizing solenoid S1.De-energization of solenoid S1 allows the valve spool in the valve V1 tobe shifted to the right, thereby allowing oil to flow to the right-handend of the cylinder 66 and to exhaust from the left-hand end so as toreturn the slide 46 to the left-hand position. As the slide 46approaches its left-hand position, it once again engages the plunger 64-and thereby closes switch LS3 to reestablish the circuit by means ofwhich relay CRI is energized to initiate another cycle of operation.Thus, slide 46 continues to reciprocate back and forth so long as switchSW3 remains closed.

In order to effect a single cycle of operation of the dressing tool 40,the starting push button PBI may be depressed momentarily with switchSW3 open as shown in FIG. 6 to energize relay CRI which remainsenergized as 7 described above until the holding circuit therefor isinterrupted by opening switch L52. W-hen the dressing tool is actuatedby closing push button PE1, it comes to rest after one full cycle ofoperation because the closing of switch L83 at the end of the cycle doesnot re-establish a cricuit which will energize relay CRL When it becomesnecessary to interrupt a truing cycle for any reason before the cycle iscompleted, the stop push button FB2 may be depressed momentarily tointerrupt the holding circuit for relay CR1 with the result that theslide 46 is returned immediately to its left-hand position.

At the end of each dressing cycle, that is, its movement from left toright and back again, which completes a cycle, the grinding wheel isadvanced toward the worlr support to compensate for any reduction inradius of the wheel due to removal of the material from its surface bythe dressing tool. For this purpose there is a cam 168 (FIG. 6) on theslide 46 which operates on the return stroke of the slide, that is,movement from right to left to rock a lever arm 17 il which momentarilycloses a normally open switch LS4. If switch SWS is closed, as shown inFIG. 6, switch LS-t supplies current by way of switch SWS to a relay CK2which, when energized, shifts normally open contacts 2CR to the left toa closed position. Current is then supplied through the contacts 2CRfrom line L1 to the solenoids S2 and S3 of valves V2 and V3, and aholding circuit for relay CR?, is established through normally closedcontacts SCR. Energization of solenoid S3 shifts the spool in the valveV3 to the left so as to supply oil through conductor C3 to the left endof the cylinder 168 which operates by displacing the piston 110 thereinand the shaft 102 toward the right to advance the stylus 72 forwardly bythe predetermined amount previously referred to. At the same time oil issupplied through conductor C4 to one end of a valve chamber 172 in avalve block 174. The valve block 174 is arranged to move between a pairof xed stops 176-176 and is supported therebetween upon three valve rods178, 179 and 181, one of which, 178, is fixed to one of the stops andoccupies the chamber 172 and the other two of which, 179 and 181, arefixed to the opposite stop 176 and occupy the chambers 18B and 182 atthe opposite sides of the valve block. Delivery of oil to the closed endof the chamber 172 moves the valve block upwardly as seen in FIG. 6,thereby forcing the valve rods 179 and 181 into the chambers 139 and 182so that oil occupying these chambers, which are of equal volume, isdisplaced therefrom through conductors CS and C6 to the valve V2, thespool of which has been displaced toward the left by energization ofsoienoid S2 concurrent with energization of solenoid S3 and thence byway of the conductors C7 and CS to the compensator chamber 134 and thesensing cylinder 124 respectively, thus moving the stylus and the wheelslide through equal distances toward the grinding wheel and work supportrespectively. Maintenance of this relationship is assured by the factthat the pistons 122 and 132 are of the same area at the ends exposed tooil pressure.

When the stylus 72 contacts the surface of the grinding wheel itproduces a signal which through a crystal pick-up and amplifier (PEG. 6)energizes a relay CRS. While the crystal pick-up may in fact be attachedto or incorporated in the stylus 72, this element of the device issimply illustrated schematically in FlG. 6, because the details of thisdevice formed no part of the instant invention. Energization of relayCRE opens normally closed contacts SCR cutting ofi the supply of currentfrom the line L1 and hence de-cnergizing relay CR2 which in turnde-energizes solenoids S2 and S3. De-energization of S2 and S3 allowsthe spools of the valves V2 and "J3 to shift to the right. Valve V3,when shifted to the right, allows oil to vent from the chamber 172 andsupplies oil to chambers 18S and 182 so that the valve block is moveddownwardly to its initial position as shown in FIG. 6. Valve V2, whichis also shifted to the right, blocks oil from exhausting from thechambers 18() and 132 and allows oil from the cylinders 124 and 134 tovent to the reservoir so that the respective mechanisms controlledthereby are reset.

Simultaneously oil is allowed to vent from the cylinder' 10S through thevalve V3 to the reservoir so that the spring 5 114 shifts the shaft 102to the left thereby retracting the stylus by the aforesaid predetermineddistance of 0.01".

It should be understood that the above description of the preferredembodiment of the instant invention as illustrated in the accompanyingdrawings presupposes a machine configuration in which the sensing device79 is so disposed that the stylus 72 is displaced radially of thegrinding wheel through successive distances equal to succeedingreductions in the radius of the grinding wheel; in which the line ofcontact between the grinding wheel 14- and the work piece W eitherintersects or lies very close to a line intersecting the respective axesof rotation of the grinding wheel 14 and the worl: piece W; and in whichthe grinding wheel 14 is fed toward the work piece W along the lineintersecting the axes of rotation of the grinding wheel 14 and the workpiecev W respectively. Under such conditions the distance through lwhichthe grinding wheel 14 is advanced to compensate for reduction in wheelsize must be equal to the distance through which the stylus 72 is movedin sensing this reduction in wheel size. On the other hand, in a machineconfiguration in which other design considerations dictate a differentdisposition of the sensing device 76 or a different disposition of thework piece relative to the grinding wheel, any such differences shouldbe taken into account in designing the pistons 122 and 132 and thecylinder chambers with which they cooperate as well as the components ofthe coordinnated control means for the concurrent actuation of thesepistons so that the displacements of the respective pistons are properly-proportioned if the particular machine configuration requires that theynot be equal.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the `appended claims.

What is claimed is:

l. In a grinding machine, a work support, means mounting a grindingwheel at a predetermined position relative to the work support forfeeding movement, a tool operable to dress the face of the grindingwheel, and sensing means operable at the end of each dressing operationto advance the mounting means independently of said feeding movementtoward the support by the amount that the face of the grinding wheel isdisplaced relative to the mounting means due to dressing.

2. In a grinding machine, a work support, means mounting a grindingwheel at a predetermined position relative to the work support forfeeding movement, means for effecting feeding movement, a tool arrangedto be moved transversely of the face of the grinding wheel to dress thegrinding wheel, means for effecting a cycle of movement of the tool, anda sensing device operable to advance the grinding wheel toward the worksupport independently of said feeding means by an amount correspondingto thc displacement of the face of the grinding wheel effected by thedressing cycle, operation of said sensing means being initiated at theend of each dressing cycle.

3. in a grinding machine, a work support, means mounting a grindingwheel at a predetermined position relative to the work support forfeeding movement, means for effecting movement of the mounting means, atool arranged to be moved transversely of the face of the grinding wheeland back to dress the face of the grinding wheel, means for effecting acycle of movement of the tool, a sensing device movable toward the faceof the grinding wheel, means operable at the end of each dressing cycleto produce concurrent corresponding movements of the sensing device andthe grinding wheel, and means operable by engagement of the sensingdevice with the face of the grinding wheel to terminate said movements.

4. In a grinding machine, a work support, means mounting a grindingwheel at a predetermined position relative to the work support forfeeding movement, means for eiecting feeding movement of the mountingmeans, a tool arranged to be moved transversely of the face of the wheeland back to dress the wheel, means for effecting a cycle of movement ofthe tool, a sensing device movable toward the wheel, means `foreffecting movement of the sensing device and of the Wheel in unison inproportionate amounts toward the Wheel and toward the Work respectively,means for initiating such movement at the end of a dressing cycle, andmeans for terminating such movement when the sensing device touches theface of the wheel.

ln a grinding machine, avvork support, means mounting a grinding wheelat a predetermined position relative to the Work support for feedingmovement, a tool arranged to be moved transversely of the face of theWheel `and back to dress the wheel, means for effecting a cycle ofmovement of the tool, a sensing stylus movable toward the wheel, drivemeans for effecting movement of the sensing stylus and the wheelproportionate Iamounts, the one toward the grinding wheel and the othertoward the work support, means for intiating operation o-f the drivemeans at the end of a dressing cycle, and means operable when the stylustouches the grinding Wheel to terminate operation of said drive means.

6. Apparatus according to claim 5, wherein the stylus is yieldablysupported.

7. In a grinding machine, a Work support, means mounting a grindingwheel at a predetermined position relative to the Work support, a toolarranged to be moved transversely of the face of the wheel and back todress the wheel, means for effecting `a cycle of movement of the tool, asensing stylus movable toward the Wheel, fiuid motors operable to effectmovement of the sensing stylus and wheel corresponding amounts, the onetoward the wheel and the other toward the work support, means operableat the end of a dressing cycle to effect operation of the fluid motorsand means operable when the stylus moves into engagement With the Wheelto terminate operation of the uid motors.

8. In a grinding machine, a work support, means mounting a grindingWheel at a predetermined position relative to the work support, a toolarranged to move transversely of the face of the Wheel and back to dressthe wheel, means for effecting a cycle of movement of the tool, asensing stylus movable toward the Wheel, uid motors operable to effectconcurrent movement of the sensing stylus and wheel proportionateamounts, valve means operable to control the flow of pressure fluid tothe motors, means operable at the end of a dressing cycle to effectoperation of the valve means to supply fluid pressure to the motors in adirection to advance the stylus and the Wheel, and means operable byengagement of the stylus with the wheel to render the fluid motor meansinoperative.

9. In a grinding machine, a work support, means mounting a grindingWheel at a predetermined position relative to the Work support, a toolarranged to move transversely of the face of the wheel and back to dressthe wheel, means for effecting a cycle of movement of the tool, asensing stylus movable toward the Wheel, fluid motors operable to effectconcurrent movement of the sensing stylus and the Wheel correspondingamounts, valves and valve actuating means operable to supply fluidpressure to the motors in directions to advance the stylus and wheel,means movable With thetool in reciprocation to effect actuation of saidvalve operating means at the end of a dressing cycle, and means operablewhen the stylus touches the wheel to render said valve actuating meansinoperative.

l0. ln a grinding machine, a work support, means mounting a grindingWheel at a predetermined position relative to the work support, a toolarranged to move transversely of the face of the Wheel and back to dressthe Wheel, means for effecting a cycle of movement of the tool, asensing stylus movable toward the wheel, fluid motors operable rst toadvance the stylus a predetermined amount and then operable to effectconcurrent corresponding movement of the sensing stylus toward the Wheeland of the Wheel toward the Work support, means movable with thedressing tool operable at the end of a dressing cycle to effectoperation of the motors, means operable by contact of the stylus withthe face of the Wheel to render the motors inoperable, and meansoperable When the motors are rendered inoperable to retract the stylussaid predetermined amount.

l1. In a grinding machine, a Work support, a grinding Wheel, a slidemounting the grinding Wheel for movement toward the work support, meansfor effecting movement of the slide toward the work support, a dressingtool, a cross-slide mounting the dressing tool for movement transverselyof the face of the wheel and back to dress the wheel, a motor means foreffecting a cycle of reciprocation of the cross-slide, a sensing stylusmovable toward the face of the wheel, mechanism operable 1ndeoendentlyof the rst named means to advance the slide and hence the wheel towardthe work support, motor-s operable to effect coordinated concurrentmovement of the stylus and said mechanism to advance the stylus andslide toward the Wheel and toward the work support respectivelycorresponding amounts, means on the cross-slide operable at the end of acycle of movement of the dressing tool to effect operation of the motorsand means operable by contact of the stylus vvith the face of the Wheelto render said motors inoperative and to retract the stylus from thewheel by a predetermined amount.

l2. In a grinding machine, a Work support, a grinding Wheel, a slidemounting the wheel for movement toward the support, means for effectingmovement of the slide toward the support to feed the Wheel toward theWork, a dressing tool, a cross-slide mounting the dressing tool formovement transversely of the face of the wheel and back Ito dress thewheel, a first motor for effecting a cycle of reciprocation of thecross-slide, a stylus occupying a retracted position with respect to theWheel, a first mechanism for moving the stylus toward the Wheel, asecond mechanism for moving the wheel slide toward the work supportindependently of the first-named means, a second motor operable toeffect an initial operation of' the mechanism for moving the stylus toadvance the stylus an amount corresponding to the distance it has beenretracted from the Wheel, third and fourth motors respectively operableto effect operation of said first mechanism to move the stylus furthertoward the wheel and said second mechanism to move the slide acorresponding amount toward the work support, means operated by contactof the stylus With the wheel to render inoperable the motors operatingsaid mechanisms, and means operable when these motors are renderedinoperable to return said stylus to its retracted position.

No references cited.

